The present invention relates generally to methods and systems for controlling a network gatekeeper. More particularly, the present invention relates to methods and systems for controlling message processing by an H.323 gatekeeper.
H.323 is a set of recommendations from the International Telecommunications Union (ITU) for multi-media communications over local area networks (LANs) that do not provide guaranteed quality of service (QoS). These networks are commonly used in corporate and educational institutions. Exemplary packet-switched networks that do not guarantee quality of service include TCP/IP, UDP/IP, and IPX over Ethernet, Fast Ethernet and Token Ring. H.323 provides recommendations for communication between voice-only handsets, video conferencing stations, and other devices capable of transmitting voice, video, and data packets over such networks.
H.323 defines four major components for a network-based communication system: terminals, gateways, gatekeepers, and multi-point control units. Terminals are client endpoints connected to a LAN that provide real-time, two-way communications. A terminal may include a telephone capable of transmitting voice packets over a network, a video conferencing station capable of transmitting voice and video over a network, or a computer capable of transmitting voice, video, and data over a network. A gateway is an optional element of an H.323 network that provides translation between transmission formats and between communications procedures. For example, a gateway may establish links between H.323 terminals and analog public switched telephone network (PSTN) terminals. Thus, gateways function as translators between H.323 compliant devices and non-H.323 compliant devices.
A gatekeeper is the most important part of an H.323 enabled network. An H.323 gatekeeper functions as the central point for all calls within its zone and provides call control services to the registered endpoints. FIG. 1 illustrates a conventional H.323 gatekeeper and an H.323 zone. In FIG. 1, an H.323 gatekeeper 100 manages message traffic in an H.323 zone 101. An H.323 zone is defined by the collection of terminals, gateways, and multi-point control units managed by a single gatekeeper.
In the illustrated example, the H.323 zone 101 spans multiple networks 102 and 103 connected by routers 104 and 105. The H.323 zone 101 includes terminals 106-110 that transmit packets containing multi-media data to each other in accordance with H.323 recommendations. A gateway 111 translates between transmission formats and communications procedures. A multi-point control unit (MCU) 112 supports conferences between three or more endpoints.
Gatekeepers perform two important call control functions. The first function is address translation from LAN aliases for terminals and gateways to IP or IPX addresses, as defined in the Registration, Admission, Status (RAS) specifications included in ITU Recommendation H.225. The second function is bandwidth management, which is also described in ITU Recommendation H.225. For example, a network manager may have a specific threshold for the number of simultaneous conferences on a local area network (LAN). The gatekeeper can refuse to make connections once the threshold is reached. The effect of refusing to make connections is to limit the total conferencing bandwidth to some fraction of the total available network bandwidth. The remaining bandwidth may be used for e-mail, file transfers, and other LAN protocols.
An optional, but valuable, feature of a gatekeeper is the ability to route H.323 calls. By routing a call through a gatekeeper, the call can be controlled more effectively. Service providers need this ability in order to bill for calls placed through their networks. This service can also be used to re-route a call to another endpoint if a called endpoint is unavailable. In addition, a gatekeeper capable of routing H.323 calls can assist in making decisions involving balancing among multiple gateways. For instance, if a call is re-routed through a gatekeeper, that gatekeeper can then re-route the call to one of the many gateways based on a balancing algorithm. While a gatekeeper is logically separate from H.323 endpoints, vendors may incorporate gatekeeper functionality into physical implementation of gateways and MCUs.
A gatekeeper is not required in an H.323 system. However, if a gatekeeper is present, terminals must make use of the services offered by the gatekeepers. RAS, as described in ITU Recommendation H.225, defines these services as address translation, admissions control, bandwidth control, and zone management.
Gatekeepers can also play a role in multi-point communications. To support multi-point conferences, users may employ a gatekeeper to receive control channels from two terminals in a point-to-point conference, as described in ITU Recommendation H.245. When the conference switches to multi-point, the gatekeeper can direct the H.245 control channel to a multi-point controller, or MC. The gatekeeper need not process the H.245 signaling; it only needs to pass the H.245 signals between the terminals or between the terminals and the MC.
LANs containing gateways can also contain a gatekeeper to translate incoming E.164 addresses to transport addresses. Because a zone is defined by its gatekeeper, H.323 entities that contain an internal gatekeeper require a mechanism to disable the internal function so that if there are multiple H.323 entities that contain a gatekeeper on a LAN, the entities can be configured into the same zone. Tables 1 and 2 shown below illustrate required and optional gatekeeper functions, respectively.
Because gatekeepers execute on one or more physical machines, the processing ability of a gatekeeper is limited. In light of all of the important functions performed by a gatekeeper, it is preferable to define methods for controlling gatekeeper message processing and for preventing the gatekeeper from crashing during overload conditions. As used herein, the phrases xe2x80x9coverload conditionsxe2x80x9d and xe2x80x9coverloaded statexe2x80x9d refer to the consumption of a percentage of gatekeeper processing capacity. For example, if the processing capability of the machine on which the gatekeeper executes is seventy percent consumed, the gatekeeper might be determined to be in an overloaded state.
One conventional method for preventing a gatekeeper from crashing during overload conditions is to cease accepting incoming messages when the gatekeeper is overloaded. One problem with this approach is that there is no mechanism for favoring calls in progress over newly originating calls. As a result, calls that are almost complete are abandoned with equal frequency as newly originating calls. The equal frequency of abandonment wastes network resources and results in loss of revenue by the service provider.
Another conventional approach for managing a network gatekeeper in overload conditions is to discard messages received by a gatekeeper based on message type. One problem with this approach is that the message type alone does not determine the semantics of the message. For example, a Setup message normally corresponds to a call origination. However, if emergency 911 is active, the Setup message can be a reconnect to the emergency operator, as opposed to a new call request. A management program that identifies and discards Setup messages based on message type only can thus discard emergency 911 reconnect Setup messages in addition to new origination Setup messages. Discarding emergency 911 reconnect Setup messages is undesirable. Because the message type alone might not provide sufficient information to determine whether to discard an incoming message, discarding calls based solely on message type might not be an effective way to regulate gatekeeper message processing during overload conditions.
Accordingly, there exists a long felt need for methods and systems for controlling gatekeeper message processing during overload conditions.
The present invention provides methods and systems for controlling gatekeeper message processing, especially during overload conditions. In order to reduce the likelihood of gatekeeper failure in overload conditions, lines of defense can be provided for regulating incoming message traffic. One line of defense includes discarding incoming messages in a manner structured to favor calls in progress over newly originating calls. Another line of defense includes prioritizing calls based on user profile or called party destination address. Prioritizing incoming calls can include preferentially allocating gatekeeper processing resources to calls of higher priority. Another line of defense can include detecting and discarding abandoned calls.
According to another aspect, the present invention can include methods and systems for detecting gatekeeper faults. For example, in order to determine whether a gatekeeper""s network protocol stack is functioning properly, a ping message can be transmitted to the gatekeeper. In order to determine whether the gatekeeper is capable of receiving calls, a Gatekeeper Confirm (GCF) message can be transmitted to the gatekeeper.
Accordingly, it is therefore an object of the present invention to provide novel methods and systems for regulating gatekeeper message processing.